Flocculation Effect of Quaternary Ammonium Salts of Poly [2- (N, N dimethylamino) ethyl Methacrylate] on Kaolin Suspension

Quaternary ammonium salts of poly [2- (N, N-dimethylamino) ethyl methacrylate] (cationic polymer) were prepared by the reaction of poly [2- (N, N- dimethylamino) ethyl methacrylate] (PAEM) with various alkyl bromides with a view of obtaining good flocculants. The flocculating ability for aqueous suspensions of kaolin was investigated with respect to the structure of quaternary ammonium salt polymers by measuring the sedimentation velocity, sedimentation volume, and residual turbidity.The results obtained are as follows.1) The sedimentation velocity of cationic polymer (QPC2X) prepared from PAEM and ethyl bromide was independent of the degree of quaternization and maximum sedimentation velocity showed 3.03.2 cm/min. Of other cationic polymers (QPC6X, QPC12X, QPC18X) obtained from PAEM and higher alkyl bromides (hexyl bromide, dodecyl bromide, and stearyl bromide), cationic polymers of the lower degree of quaternization displayed the larger rate of sedimentation and the maximum rate of sedimentation showed 2.33.2 cm/min at the optimum dosage of 610 ppm. 2) The bulky precipitation was obtained with cationic polymer of the medium degree of quaternization (5070%). 3) The clearest supernatant gave 2550 ppm turbidity at the dosage of 810 ppm. 4) Cationic polymers were most effective for flocculation with the increase of acidity. 5) The sedimentation velocity decreased rapidly at the concentration of 2.55.0% of kaolin suspension. 6) Cationic polymers derived from PAEM and various alkyl bromides were more effective with the commercial flocculants such as Sumifloc-FC, Himoloc-Neo 600, and PAS-A.